Polyimide copolymers were obtained containing 1,3-bis(3-aminophenoxy)
benzene (APB) and other diamines and dianhydrides and terminating with the appropriate amount of reactive endcapper. The reactive endcappers studied include but should not be limited to 4-phenylethynyl
phthalic anhydride (PEPA), 3-aminophenoxy-4'-phenylethynylbenzophenone (3-APEB),
maleic anhydride (MA) and nadic anhydride (5-
norbornene-2,3-dicarboxylic anhydride, NA). Homopolymers containing only other diamines and dianhydrides which are not processable under conditions described previously can be made processable by incorporating various amounts of APB, depending on the chemical structures of the diamines and dianhydrides used. By simply changing the ratio of APB to the other
diamine in the
polyimide backbone, a material with a unique combination of
solubility, Tg, Tm,
melt viscosity,
toughness and elevated temperature mechanical properties can be prepared. The copolymers that result from using APB to enhance processability have a unique combination of properties that include low pressure
processing (200 psi and below), long term melt stability (several hours at 300 DEG C. for the phenylethynyl terminated polymers), high
toughness, improved
solvent resistance, improved
adhesive properties, and improved composite mechanical properties. These copolyimides are eminently suitable as adhesives, composite matrices, moldings, films and coatings.